class Vector3 {
	private:
		double x, y, z;

	public:
		Vector3();
		Vector3(double, double, double);
		Vector3 operator + (Vector3& v);
		Vector3 operator - (Vector3& v);
		double operator * (Vector3& v);
		Vector3 operator ^ (Vector3& v);
		Vector3 operator * (double a);
		friend Vector3 operator * (double a, Vector3& v);
		void print();
		double len();
};